Isistius brasiliensis
Cookiecutter Shark
Collection Details
Specimens
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Taxonomic Hierarchy
Chondrichthyes (Cartilaginous Fishes)
Squaliformes (Dogfish Sharks)
Dalatiidae (Kitefin Sharks)
Isistius
Isistius brasiliensis (Cookiecutter Shark)
Description
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Characters
Body shape: elongated. The cookiecutter shark Isistius brasiliensis is distinctive for the prominent dark collar marking around its throat, large nearly symmetrical caudal fin with a long ventral lobe over 2/3 length of dorsal caudal margin, and moderately large lower teeth in 25-32 rows. Eyes set anterior of head but sufficiently far back to lack an extensive anterior binocular field. Pectoral fins subquadrate; pelvic fins larger than dorsal fins (Ref.247). Tooth count: 30-37/25-31. Vertebral count: 81-89. Spiral valve count: 8-10 (Ref. 48844). Dark brown dorsally, paler ventrally except for blackish band across throat; tips of caudal lobe blackish (Ref. 6577). As with the other member of the genus Isistius , it has a characteristic small cigar-shaped body with two small close-set spineless dorsal fins far posterior on back, no anal fin, huge, triangular-cusped teeth without blades, short, bulbous snout and a unique suctorial lips (Ref. 247).
Distribution
Western Atlantic: Bahamas and southern Brazil. Eastern Atlantic: Cape Verde, Guinea to Sierra Leone, southern Angola and South Africa, including Ascension Island. Indo-Pacific: Mauritius to New Guinea, Lord Howe Island, and New Zealand (Ref. 26346), north to Japan and east to the Hawaiian Islands. Eastern Pacific: Easter Island (Ref. 9068) and the Galapagos.
Habitat Associations
Marine. bathypelagic. depth range 0-3700 m.
Biology
Oceanic species (Ref. 247). Epi- to bathypelagic at 1-3500 m (Ref. 58302). Makes diurnal vertical migrations from below 1,000 m in the day to or near the surface at night (Ref. 6871, 58302). Travels long vertical distances in excess of 2,000 to 3,000 m on a diel cycle (Ref. 247). Feeds free-living deepwater prey such as large squid, gonostomatids, crustaceans but is also a facultative ectoparasite on larger pelagic animals such as wahoo, tuna, billfishes, and cetaceans (Ref. 247). Ovoviviparous (Ref. 205), with 6-12 young per litter (Ref. 48844). The cookiecutter shark has specialized suctorial lips and a strongly modified pharynx that allow it to attach to the sides of it prey (Ref. 247). It then drives its saw-like lower dentition into the skin and flesh of its victim, twists about to cut out a conical plug of flesh, then pull free with the plug cradled by its scoop-like lower jaw and held by the hook-like upper teeth (Ref. 247). Teeth are shed as a complete unit; the lower teeth are swallowed, perhaps to maintain sufficient calcium levels in its body (Ref. 247). Interconnection at the bases of individual tooth allows a whole row of teeth to move if one tooth is touched. This shark is reported to radiate light for as long as three hours after its death. Not dangerous to people because of its small size and habitat preferences (Ref. 247).
Max length: 42.0 cm TL.
Reproductive mode: dioecism; fertilization: internal (oviduct); bearers (internal live bearers). Presumably ovoviviparous; 6 or 7 large eggs have been found in ovaries (Ref. 247). Distinct pairing with embrace (Ref. 205). Viviparous, without a yolk sac placenta, 6-12 young per litter. Males mature at about 36 cm, with a maximum length of 42 cm; females mature at 39 cm, with a maximum length of 56 cm. Size at birth is unknown. (Ref. 48844).
IUCN Red List Status: Least Concern (LC), assessed 2017-07-04. Resilience: Very low (Fec = 6).
Commercial or Environmental Importance
Fisheries: minor commercial.
References
Compagno, L.J.V. (1984) FAO Species Catalogue. Vol. 4. Sharks of the world. An annotated and illustrated catalogue of shark species known to date. Part 1 - Hexanchiformes to Lamniformes. FAO Fish. Synop. 125(4/1):1-249. Rome, FAO.
Strasburg, D.W. (1963) The diet and dentition of Isistius brasiliensis, with remarks on tooth replacement in other sharks. Copeia 1963(1):33-39.
Bass, A.J., L.J.V. Compagno and P.C. Heemstra (1986) Squalidae. p. 49-62. In M.M. Smith and P.C. Heemstra (eds.) Smiths' sea fishes. Springer-Verlag, Berlin.
Compagno, L.J.V. and V.H. Niem (1998) Squalidae. Dogfish sharks. p. 1213-1232. In K.E. Carpenter and V.H. Niem (eds.) FAO Identification Guide for Fishery Purposes. The Living Marine Resources of the Western Central Pacific Vol. 2. Rome: FAO.
Cortés, E. (1999) Standardized diet compositions and trophic levels of sharks. ICES J. Mar. Sci. 56:707-717.
Ebert, D.A. (2003) Sharks, rays and chimaeras of California. California Natural History Guides No. 71. University of California Press. 284 p.
Kiraly, S.J., J.A. Moore and P.H. Jasinski (2003) Deepwater and other sharks of the U.S. Atlantic Ocean Exclusive Economic Zone. Mar. Fish. Rev. 65(4):1-64.
Comments On Isistius brasiliensis